Graphics, Images, and Multimedia
http://www.usability.gov/pdfs/chapter14.pdf

Usability.gov
2006

Abstract:

Graphics are used on many, if not most, Web pages. When used appropriately, graphics can facilitate learning. An important image to show on most pages of a site is the organization's logo. When used appropriately, images, animation, video, and audio can add tremendous value to a Web site. When animation is used appropriately, it is a good idea to introduce the animation before it begins.